Yemen: Barack Obama warned that al-Qaeda planning ricin attack

The New York Times, citing classified intelligence documents and unnamed officials, reports that terrorist operatives have been making efforts to buy large quantities of castor beans – which contain the toxic ricin protein – and shift them to a remote tribal area controlled by insurgents for processing.

Ricin is so poisonous that inhalation of a few minute grains is enough to kill an adult. It was used in deadly incidents including the 1978 assassination in London of Bulgarian dissident Georgi Markov and, in 2002, was the subject of a bioterrorism scare in the UK capital following a police raid on a facility said to be plotting its manufacture.

US officials are reported to have told Mr Obama that an attack is not imminent and that the terrorist arm has yet to formulate a means for dispersing it as a weapon.

They believe that the ultimate goal is to find an effective means of packing the white powder around explosives and detonating the devices in packed public areas such as shopping malls and airports, the New York Times revealed.